A theoretical non-hydrostatic model is developed to describe the dynamics of a two-layer shallow water system in the presence of viscous and Coriolis effects. The Navier-Stokes equations are integrated over the water depth in each layer to obtain the layer-mean equations. To close the resulting equation set, perturbation expansions of the vertical momentum equation are used and the dynamic pressures are solved in terms of wave elevations and horizontal velocities. A preliminary analysis is also carried out and a result for the quasigeostrophic problems is given based on an previous study. Our final model is of the Bousinesq class which is nonlinear and dispersive, and includes the effects of surface wind stress, bottom friction, eddy diffusion and earth rotation. It is shown that our new model can be readily reduced to previous inviscid non-hydrostatic models. Our model can be used in numerical simulations to study real ocean problems such as hurricane generated waves, tidal induced current, and interactions among surface waves, internal waves and variable topographies. / Thesis (M. S.)--University of Hawaii at Manoa, 1995. / Includes bibliographical references (leaves 55-59). / UHM: Has both book and microform. / U.S. Geological Survey; project no. 06; grant agreement no. 14-08-0001-G2015

The development of a new N-Line model, which provides a practical tool for simulating regional beach changes induced by short and long-term processes, is described in this thesis. The new N-Line model consists of four main modules that together describe the hydrodynamic and morphological responses. The four constituent modules have been integrated based on a wide range of research including the utility and function of commercial or freeware models. They are RCPWAVE wave module, time-averaged and depth-integrated current module, sediment transport module based on Bailard (1981) and contour change morphological module. Two different time-scales and two staggered grid systems for hydrodynamic and morphological simulations were adopted alternatively. For short-term 2D profile changes, new N-Line model applicability has been examined using data from the laboratory to the field. For ideal beaches, new N-Line can simulate an offshore storm bar generation or an onshore accretion due to high or low energy waves. For SUPERTANK large-scale flume data, the predicted profile matched the measured profile well, especially the bar height and position. For beach profile data from the Gold Coast, storm-induced variations of barred profiles were reasonably modelled. The new N-Line model compared well with other commonly used cross-shore models such as SBEACH and UNIBEST. A new schematisation for a non-monotonic profile and DUNED inclusion were introduced. Sensitivity tests on cross-shore sediment coefficient (Kq), smoothing parameter (??s) and water level fluctuations were performed. For long-term 3D beach changes, the new N-Line model applicability has been tested with various boundary conditions using idealized and real field data. Two periods, 17 and 16 months, of beach changes before and after a major bypass plant commenced operation in 2001 at Letitia Spit were simulated. The profile and shoreline changes were predicted reasonably well. Empirical model parameters were determined after a range of sensitivity and calibration testing. The new N-Line model showed its better performance compared to one-line models. It can handle various boundary conditions, especially bypass conditions. The N-Line model is not only capable of modelling planform variations but also cross-shore profile changes.

Typescript (photocopy) / iii, 152 leaves : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.) Dept. of Applied Mathematics, University of Adelaide 1981

xii, 218 leaves / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.1978) from the Dept. of Mathematical Physics, University of Adelaide

The design and management of organised systems, comprised of dynamic interdependent collectives of autonomous agents, is the kind of problem that the discipline of complex systems is intended to address. Nevertheless, conventional model-based applications of complex systems may be of limited utility when the problem is also data-poor and soft. In this case, a quantitative model may be at best meaning-less; at worst harmful. Systems approaches, such as soft systems methodologies, have been developed that provide some guidance in this domain. However, these alternatives do not utilise the exact techniques of complex systems, preferring to abandon mathematical representations altogether. It is the aim of this thesis to advance a “conceptual analysis" approach to complex systems design that exploits deep insights from the mathematics of complex systems, without building explicit models of the underlying system. It is argued that this approach can extend the domain of applicability of the discipline of complex systems into situations where quantitative data is unavailable, and human and social factors are significant. Conceptual analysis of complex systems is inherently multidisciplinary, because it is broader than the foundations of any single conventional discipline. This is reflected in the structure of this thesis, which spans the philosophy, theory and application of complex systems. Part I on systems philosophy develops an understanding of representation, which sheds light on the utility and limitations of models. The history of the systems movement is then surveyed, systemism is distinguished from both individualism and holism, and `system' is defined. Complex systems is contrasted with both early systems theory and contemporary systems approaches. Part II on complex systems theory firstly relates the major theoretical concepts within a rigourous information theoretical framework. They include complexity, edge of chaos, self-organisation, emergence, adaptation, evolution and self refer- entiality. The central systems concept - emergence - is then examined in depth beyond its information theoretic interpretation, leading to a concise definition of emergent properties and emergence. A new framework for understanding emergence in terms of scope, resolution and state yields substantial novel insights. It is shown that emergence is coupled to scope, in contrast to the conventional explanation that relates levels of description. Part III applies the preceding philosophical and theoretical framework to real-world problems in the defence and security arena. In the first example, the theory of multi-scale complexity reveals structural impediments to success for conventional force structures in asymmetric warfare, such as Operation Iraqi Freedom. The second example analyses the capability development process, which is responsible for transforming the security needs of Government into equipment purchasing decisions. The analysis produces practical recommendations for improvements that address the underlying complexity of the problem. Reflections in the conclusion of this thesis focus on the interrelations between philosophy, theory and application. As the individual contributions of this thesis are woven into a single tapestry, they demonstrate the utility of a multidisciplinary approach to complex systems design. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1283989 / Thesis(PhD) -- University of Adelaide, School of Mathematical Sciences, 2007

Thesis (150-154)--University of Washington, 2007. / Vita. Includes bibliographical references (p. 150-154).

Thesis (Ph. D.)--University of Texas at Austin, 2000. / Vita. Includes bibliographical references (leaves 90-95). Available also in a digital version from Dissertation Abstracts.

Thesis (Ph.D.)--University of California, Berkeley, 1961. / "Physics, UC-34" -t.p. "TID-4500 (16th Ed.)" -t.p. Includes bibliographical references (p. 47).

The author explicitly specifies a New Keynesian style model embodying a financial constraint on the availability of equity and a financial market imperfection with regard to the existence of state-contingent assets based upon the published papers of Greenwald and Stiglitz (1988, 1990, and 1993). Using computer based numerical simulation, the author validates the three unproven Propositions found in the Greenwald and Stiglitz 1993 article with regard to the model's comparative static behaviour. Through the inclusion of a parameter for technology into the production function, the author shows that observations made by Greenwald and Stiglitz with regard to the effect of equity infusions is subject to qualification. Investigation of the model's inter-temporal behaviour reveals that the claims made by Greenwald and Stiglitz with regard to multiple periodicity are again subject to many qualifications. Linearization around the steady-state equilibrium as suggested by Greenwald and Stiglitz is shown to offer limited insight because of the implied non-linearity of the model's first order difference equation. Calibrated numerical simulation of the nonlinear difference equation reveals the potential for both single and multiple periodicity, period doubling bifurcations, and chaotic trajectories displaying sensitivity to initial conditions. In addition it was shown that the model's implied random attractor was key to understanding its inter-temporal behavior. In the Greenwald and Stiglitz articles the existence of derivative markets such as futures or options to manage risk are assumed away. The author, in order to investigate the effects of futures or options markets upon business cycles, modifies the explicitly specified model to include the use of state-contingent assets. Introducing the use of derivative financial products to manage risk, using numerical simulation, produces the surprising result that in the aggregate they may lead to slightly greater output instability. In addition to the model's structure, several intuitive reasons for these results are discussed in depth. The Greenwald and Stiglitz model also assumed that the cost of capital was not risk adjusted. The author modifies the explicitly specified model and using numerical simulation shows that like other unrealistic assumptions concerning dividend distribution, leads to alternative laws of motion. The research is concluded with discussion of possible policy and regulatory implications.

The earliest stage of software development almost always involves converting requirements descriptions written in natural language (NLRs) into initial conceptual models, represented by some formal notation. This stage is time-consuming and demanding, as initial models are often constructed manually, requiring human modellers to have appropriate modelling knowledge and skills. Furthermore, this stage is critical, as errors made in initial models are costly to correct if left undetected until the later stages. Consequently, the need for automated tool support is desirable at this stage. There are many approaches that support the modelling process in the early stages of software development. The majority of approaches employ linguistic-driven analysis to extract essential information from input NLRs in order to create different types of conceptual models. However, the main difficulty to overcome is the ambiguous and incomplete nature of NLRs. Semantic-driven approaches have the potential to address the difficulties of NLRs, however, the current state of the art methods have not been designed to address the incomplete nature of NLRs. This thesis presents a semantic-driven automatic model construction approach which addresses the limitations of current semantic-driven NLR transformation approaches. Central to this approach is a set of primitive conceptual patterns called Semantic Object Models (SOMs), which superimpose a layer of semantics and structure on top of NLRs. These patterns serve as intermediate models to bridge the gap between NLRs and their initial conceptual models. The proposed approach first translates a given NLR into a set of individual SOM instances (SOMi) and then composes them into a knowledge representation network called Semantic Object Network (SON). The proposed approach is embodied in a software tool called TRAM. The validation results show that the proposed semantic-driven approach aids users in creating improved conceptual models. Moreover, practical evaluation of TRAM indicates that the proposed approach performs better than its peers and has the potential for use in real world software development.